document.getElementById("createPlaylist").addEventListener("click", function() {
    var nextSibling = this.nextElementSibling;
    while (nextSibling) {
        if (nextSibling.tagName === "LI") {
            nextSibling.style.display = nextSibling.style.display === "none" ? "" : "none";
        }
        nextSibling = nextSibling.nextElementSibling;
    }
});